Blowing device and cleaner

ABSTRACT

A blowing device includes a mixed flow impeller that rotates about a central axis extending vertically, a motor that drives the mixed flow impeller to rotate, and an impeller cover surrounding an outside of the mixed flow impeller in a radial direction. The mixed flow impeller includes a hub portion extending outwardly in the radial direction toward a lower side in an axial direction, and moving blades juxtaposed on an outer surface of the hub portion in a circumferential direction. A minimum dimension of a first gap between the moving blade and the impeller cover at a lower end portion of the moving blade is larger than a minimum dimension of a second gap between the moving blade and the impeller cover at an upper end portion of the moving blade.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2017-142251 filed on Jul. 21, 2017. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This disclosure relates to a blowing device and a cleaner including ablowing device.

2. Description of the Related Art

An electric blowing device (blowing device) of the related art includesan impeller that is driven by a rotation shaft of a motor and a fan casethat covers the impeller. A labyrinth seal portion having a slight gapat a facing portion between a bellow portion of the impeller and anextended portion of the fan case is configured.

The labyrinth seal portion which is described above is configured, sothat a decrease in an air blowing efficiency is suppressed.

However, in the electric blowing device of the related art, when acentrifugal force is applied to the impeller during rotation of theimpeller and thereby a shape of the impeller is deformed, there is apossibility that a gap between an impeller blade (blade) and an impellercover cannot be kept appropriately. Therefore, there is a possibilitythat the air blowing efficiency is decreased due to the contact.

SUMMARY OF THE INVENTION

A blowing device according to a preferred embodiment of the presentinvention includes a mixed flow impeller that rotates about a centralaxis extending vertically; a motor that drives the mixed flow impellerto rotate; and an impeller cover surrounding an outside of the mixedflow impeller in a radial direction. The mixed flow impeller includes ahub portion that extends outwardly in the radial direction toward alower side in an axial direction, and a plurality of moving blades whichare juxtaposed on an outer surface of the hub portion in acircumferential direction. A minimum dimension of a first gap betweenthe moving blade and the impeller cover at a lower end portion of themoving blade is larger than a minimum dimension of a second gap betweenthe moving blade and the impeller cover at an upper end portion of themoving blade.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cleaner according to a preferredembodiment of the present invention.

FIG. 2 is a perspective view of a blowing device according to thepreferred embodiment of the present invention.

FIG. 3 is a vertical sectional view of the blowing device illustrated inFIG. 2.

FIG. 4 is an exploded perspective view of the blowing device illustratedin FIG. 2.

FIG. 5 is a perspective view of a motor housing and a stator core asviewed from below.

FIG. 6 is a perspective view of the motor housing as viewed from above.

FIG. 7 is a perspective view of the motor housing as viewed from below.

FIG. 8 is a perspective view of an impeller.

FIG. 9 is an enlarged sectional view of a cross section (cross sectionincluding a central axis C) along a radial direction of the motorhousing and a circumferential portion of the impeller.

FIG. 10 is a perspective view of the blowing device in a state where animpeller cover is removed.

FIG. 11 is s side view of the blowing device illustrated in FIG. 10.

FIG. 12 is a schematic sectional view of a state where balanceadjustment of the impeller is performed.

FIG. 13 is a plan view of the impeller.

FIG. 14 is a plan view illustrating a modification example of a topplate recess portion.

FIG. 15 is a sectional view of the top plate recess portion in acircumferential direction.

FIG. 16 is an enlarged sectional view of a cross section (cross sectionincluding a central axis) along a radial direction of the motor housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the drawings. In thisspecification, in a blowing device A, a direction parallel to a centralaxis C of the blowing device A is referred to as an “axial direction”, adirection orthogonal to the central axis C of the blowing device A isreferred to as a “radial direction”, and a direction along a circulararc with the central axis C of the blowing device A as a center isreferred to as a “circumferential direction”. Similarly, also withrespect to an impeller 20, in a state of being incorporated in theblowing device A, respective directions coinciding with the axialdirection, the radial direction, and the circumferential direction ofthe blowing device A are simply referred to as an “axial direction”, a“radial direction”, and a “circumferential direction”. In addition, inthis specification, in the blowing device A, a shape and a positionalrelationship of each portion will be described with the axial directionas a vertical direction, and an intake port 43 side of an impeller cover41 with respect to the impeller 20 as an upper side. The verticaldirection is simply used for explanation and does not limit a positionalrelationship and direction in a use state of the blowing device A. Inaddition, an “upstream side” and a “downstream side” respectivelyindicate upstream and downstream in a flowing direction of air drawnfrom the intake port 43 when the impeller 20 is rotated.

In this specification, in a cleaner 100, the shape and the positionalrelationship of each portion will be described with a directionapproaching a floor surface F (surface to be cleaned) of FIG. 1 as“downward” and a direction away from the floor surface F as “upward”.These directions are merely used for explanation and do not limit thepositional relationship and the directions in the use state of thecleaner 100. In addition, the “upstream” and the “downstream”respectively indicate upstream and downstream in the flowing directionof the air drawn from an intake portion 103 when the blowing device A isdriven.

The cleaner of the exemplary embodiment of this disclosure will bedescribed below. FIG. 1 is a perspective view of the cleaner accordingto the embodiment. The cleaner 100 is a so-called stick type electriccleaner and includes a casing 102 in which the intake portion 103 and anexhaust portion 104 are respectively opened to a lower surface and anupper surface. A power supply cord (not illustrated) is led out from aback surface of the casing 102. The power supply cord is connected to apower supply outlet (not illustrated) provided on a side wall surface ofa living room or the like, and supplies power to the cleaner 100.Moreover, the cleaner 100 may be a so-called robot type, canister type,or handy type electric cleaner.

An air passage (not illustrated) for connecting the intake portion 103and the exhaust portion 104 is formed in the casing 102. A dustcollecting portion (not illustrated), a filter (not illustrated), andthe blowing device A are disposed in order from the upstream side to thedownstream side in the air passage. Trash such as dust contained in theair circulating through the air passage is shielded by the filter and iscollected in the dust collecting portion formed in a container shape.The dust collecting portion and the filter are configured to beattachable and detachable to and from the casing 102.

A grip portion 105 and an operation portion 106 are provided on an upperportion of the casing 102. A user can grasp the grip portion 105 andmove the cleaner 100. The operation portion 106 has a plurality ofbuttons 106 a and operation setting of the cleaner 100 is performed byoperating the buttons 106 a. For example, a driving start, a drivingstop, a change in a rotational speed, and the like are instructed byoperations of the buttons 106 a. A cylindrical suction pipe 107 isconnected to the intake portion 103. A suction nozzle 110 is detachablyattached to the suction pipe 107 at an upstream end (lower end in thedrawing) of the suction pipe 107.

FIG. 2 is a perspective view of the blowing device according to theembodiment. FIG. 3 is a vertical sectional view of the blowing deviceillustrated in FIG. 2. FIG. 4 is an exploded perspective view of theblowing device illustrated in FIG. 2. The blowing device A is mounted onthe cleaner 100 to suck the air.

The blowing device A includes a motor 10, the impeller 20, a motorhousing 30, a blower housing 40, a cover member 50, an intermediatemember 70, and a board Bd.

The impeller 20 and the motor housing 30 are stored in an inside of theblower housing 40. As illustrated in FIG. 3, a flow path 60 is formed ina gap between the blower housing 40 and the motor housing 30. The flowpath 60 communicates with the impeller cover 41 which is described laterat an upper end (upstream end) and an exhaust port 61 is formed at alower end (downstream end) of the flow path 60.

The motor 10 connected to the impeller 20 is stored in the motor housing30. The impeller 20 rotates about the central axis C extendingvertically. That is, the mixed flow impeller 20 is capable of rotatingabout the central axis C extending vertically. The motor 10 is disposedbelow the impeller 20 to rotate the impeller 20. That is, the impeller20 is rotated by the rotation of the motor 10. That is, the impeller 20rotates about the central axis C extending vertically in a rotationdirection R (see FIG. 8 which is described later) by the rotation of themotor 10. An airflow generated by rotation of the impeller 20 isdischarged from the exhaust port 61 through the flow path 60.

As illustrated in FIG. 3, the motor 10 stored in the motor housing 30 isdisposed below the impeller 20. That is, the motor 10 is disposed belowthe mixed flow impeller 20 and the motor housing surrounding the outsideof the motor 10 in the radial direction is disposed. The motor 10 is aso-called inner rotor type motor. The motor 10 includes a shaft 11, arotor 12, and a stator 13.

The shaft 11 has a cylindrical shape. The shaft 11 extends along thecentral axis C. As illustrated in FIG. 3, the shaft 11 penetrates athrough-hole 316 provided in a motor housing top plate 31 of the motorhousing 30, which is described later. The impeller 20 is fixed to an endportion of the shaft 11 protruding from the motor housing top plate 31.The shaft 11 is rotatably supported by an upper bearing Br1 and a lowerbearing Br2. That is, the upper bearing Br1 rotatably supports the shaft11. The lower bearing Br2 is disposed below the upper bearing Br1 androtatably supports the shaft 11.

The upper bearing Br1 and the lower bearing Br2 are ball bearings. Theshaft 11 is fixed to inner races of the upper bearing Br1 and the lowerbearing Br2. For fixing, means such as adhesion insertion or pressfitting is adopted. An outer ring of the upper bearing Br1 is fixed tothe motor housing 30 and an outer ring of the lower bearing Br2 is fixedto the cover member 50. Moreover, the upper bearing Br1 and the lowerbearing Br2 are not limited to ball bearings. At least a part of theupper bearing Br1 is disposed in a lower surface recess portion 211 ofthe impeller 20, which is described later. That is, at least a part ofthe upper bearing Br1 is disposed in the lower surface recess portion211. Therefore, lengths of the upper bearing Br1 and the lower bearingBr2 in the axial direction can be increased. In addition, the upperbearing Br1 can be disposed close to a boss portion 212 of the impeller20, which is described later. Therefore, deformation such as deflectionof the shaft 11 when the impeller 20 rotates can be suppressed.

The rotor 12 is fixed to the shaft 11. The rotor 12 rotates togetherwith the shaft 11. The rotor 12 has a plurality of magnets (notillustrated). The plurality of the magnets are fixed to an outerperipheral surface of the shaft 11. In the plurality of the magnets, amagnetic pole surface of an N pole and a magnetic pole surface of an Spole are alternately arranged.

Moreover, instead of the plurality of the magnets, a single annularmagnet may be used. In this case, in the magnet, the N pole and the Spole may be alternately magnetized in the circumferential direction. Inaddition, the magnet may be integrally molded with resin mixed withmagnetic powder.

FIG. 5 is a perspective view of the motor housing 30 and the stator core131 as viewed from below. The stator 13 is disposed on an outside of therotor 12 in the radial direction. The stator 13 includes a stator core131, an insulator 132, and a coil 133. The stator core 131 is alaminated body in which electromagnetic steel plates are laminated inthe axial direction (vertical direction in FIG. 3). Moreover, the statorcore 131 is not limited to the laminated body in which theelectromagnetic steel plates are laminated and, for example, may be asingle member such as powder calcination or casting.

The stator core 131 has an annular core back 134 and a plurality ofteeth 135. The plurality of the teeth 135 extend inwardly in the radialdirection from an inner peripheral surface of the core back 134 towardthe magnet (not illustrated) of the rotor 12. Therefore, the pluralityof the teeth 135 are disposed in the circumferential direction. The coil133 is formed by winding a conductive wire around each of the teeth 135via the insulator 132.

Moreover, the motor 10 is a brushless motor. The brushless motor isdriven by a current divided into three systems (hereinafter, referred toas three phases) having different supply timings. The coil 133 and themagnet of the rotor 12 attract or repel each other by supplying acurrent to a plurality of the coils 133 at a determined timing, so thatthe rotor 12 rotates. The motor 10 is, for example, a high-revolutiontype motor capable of rotating at a revolution number of 100,000revolutions per minute or more. Normally, in the motor 10, the smallerthe number of the coils 133, the more advantageous for high-speedrotation. The motor 10 is controlled with a three-phase current.Therefore, in the motor 10, the number of the coils 133 and the teeth135 in which the coils 133 are disposed is three. That is, the motor 10is a three-phase and three-slot motor. Moreover, three teeth 135 aredisposed with equal intervals in the circumferential direction in orderto be rotated in a balanced manner.

In the stator core 131, an inner peripheral surface and an outerperipheral surface of the core back 134 are flat surfaces in thevicinity of a base of the teeth 135. Therefore, it is possible toeffectively utilize a winding space. In addition, loss can be reduced byshortening a magnetic path. In addition, it is possible to preventwinding collapse of the coil 133 while preventing disturbance of amagnetic distribution. In addition, the inner peripheral surface and theouter peripheral surface of the core back 134 other than the vicinity ofthe base of the teeth 135 are curved. The curved portion of the coreback 134 is in contact with an inner surface of the motor housing 30. Inthis case, the curved portion may be press-fitted to the inner surfaceof the motor housing 30. Moreover, the press-fitting may be a so-calledinterference fitting, or light fitting, which is a so-calledintermediate fitting in which a force due to press fitting is weakerthan that of the interference fitting. Moreover, the core back 134 mayhave a cylindrical shape without a flat surface. In this case, thecylindrical outer surface is press-fitted into the motor housing 30.Moreover, the core back 134 and the motor housing 30 may be fixed byanother method such as insertion bonding.

A lead wire (not illustrated) is connected to the coil 133. One end ofthe lead wire is connected to a drive circuit (not illustrated) on theboard Bd disposed below the blower housing 40. Therefore, power issupplied to the coil 133.

FIG. 6 is a perspective view of the motor housing as viewed from above.FIG. 7 is a perspective view of the motor housing as viewed from below.As illustrated in FIGS. 3, 5, 7, and the like, the motor housing 30covers an outside of the motor 10 in the radial direction. The motorhousing 30 includes the motor housing top plate 31 and a motor housingcylindrical portion 32. The motor housing top plate 31 expands in adirection orthogonal to the central axis. The motor housing top plate 31has a circular shape as viewed from the axial direction. The motorhousing cylindrical portion 32 extends downwardly in the axial directionfrom an outer edge in the radial direction of the motor housing topplate 31. The motor housing top plate 31 and the motor housingcylindrical portion 32 are a molded body which is integrally formed. Themotor housing 30 can be made of metal, resin, or the like.

Here, in a case where the motor housing 30 is made of metal, a metalconfiguring the motor housing 30 can be, for example, an aluminum alloyor a magnesium alloy. The aluminum alloy and the magnesium alloy areeasy to mold, lightweight, and inexpensive compared to other metals.

The motor housing top plate 31 includes a top plate upper surface 310.The top plate upper surface 310 includes a first top plate inclinationsurface 311 and a second top plate inclination surface 312. The firsttop plate inclination surface 311 has a conical shape inclined inwardlytoward an upper side along the axis. In addition, the second top plateinclination surface 312 has a conical shape inclined outwardly towardthe upper side along the axis. The first top plate inclination surface311 and the second top plate inclination surface 312 are connected atlower end portions in the axial direction. That is, the motor housingtop plate 31 includes an annular recess portion. The annular recessportion is substantially V-shaped which is recessed downwardly.

In addition, the top plate upper surface 310 includes a top plate recessportion 313. The top plate recess portion 313 extends from an outer edgein the radial direction to the inside in the radial direction of the topplate upper surface 310. Details of the top plate recess portion 313will be described later.

The motor housing top plate 31 includes a top plate facing portion 314facing the rotor 12 and the stator 13 of the motor 10 in the axialdirection. The top plate facing portion 314 is a lower surface of themotor housing top plate 31. The top plate facing portion 314 includes acenter recess portion 315 which is recessed upward at a center portionand the through-hole 316 penetrating in the axial direction. The outerring of the upper bearing Br1 is fixed to the center recess portion 315.The shaft 11 penetrates the through-hole 316. The central axes of thecenter recess portion 315 and the through-hole 316 coincide. Inaddition, the top plate facing portion 314 includes a facing recessportion 317 which is recessed upward. The intermediate member 70 isinserted into the facing recess portion 317. The top plate facingportion 314 includes three facing recess portions 317 and the threefacing recess portions 317 are disposed with equal intervals in thecircumferential direction around the central axis C. Moreover, as willbe described in detail later, the facing recess portion 317 is disposedat a position overlapping with the coil 133, that is, the teeth 135 inthe axial direction when the stator core 131 is fixed to the motorhousing 30.

The motor housing cylindrical portion 32 is cylindrical. An upper endportion of the motor housing cylindrical portion 32 in the axialdirection is connected to the motor housing top plate 31. That is, themotor housing 30 has a bottomed cylindrical shape of which a lower sideis opened. The stator core 131 is press-fitted to the inner peripheralsurface of the motor housing top plate 31. In addition, the motorhousing cylindrical portion 32 includes an axial direction contactportion 321 at a lower portion thereof. The axial direction contactportion 321 protrudes inwardly in the radial direction. As illustratedin FIGS. 3 and 5, the axial direction contact portion 321 is in contactwith a lower end surface of the stator core 131 in the axial directionto suppress a downward movement of the stator core 131. The intermediatemember 70 is disposed between the upper side of the stator 13 in theradial direction and the top plate facing portion 314. The stator 13 ispressed downwardly in the axial direction by an elastic force of theintermediate member 70. The axial direction contact portion 321 appliesa force to the stator 13 in a direction opposite to a direction of theelastic force from the intermediate member 70.

In addition, as illustrated in FIG. 5, the motor 10 includes a pluralityof the axial direction contact portions 321. More specifically, threeaxial direction contact portions 321 are provided at positionsoverlapping portions of the stator core 131 of the motor housingcylindrical portion 32, which are in contact with the motor housing 30.The three axial direction contact portions 321 are disposed with equalintervals in the circumferential direction, so that a force can beapplied from the axial direction contact portion 321 to the stator core131. Therefore, a uniform or substantially uniform force can be appliedto the stator core 131 in the circumferential direction.

Moreover, the axial direction contact portion 321 may be in contact witha surface facing downwardly the stator core 131 in the axial directionand is not limited to a simple surface. In addition, the axial directioncontact portion 321 is in contact with the stator core 131, but it isnot limited thereto. For example, in a case where the insulator 132 orthe coil 133 has sufficient strength, the axial direction contactportion 321 may be in contact with the insulator 132 or the coil 133.

In addition, the axial direction contact portion 321 protrudes inwardlyin the radial direction in advance, and may have a shape to be pressedby the stator core 131 in the radial direction when the stator core 131,that is, the stator 13 is attached. In addition, after the stator core131 is attached to the motor housing 30, an entirety or a part of theaxial direction contact portion 321 may be bent in the circumferentialdirection. In addition, it is not limited to bending and the downwardmovement of the stator core 131 in the axial direction may be suppressedby caulking.

A plurality of stationary blades 33 are provided on an outer peripheralsurface 300 of the motor housing 30. The stationary blade 33 is formedin a plate shape and is inclined in a direction opposite to the rotationdirection of the impeller 20 toward the upper side. The stationary blade33 is convexly curved on the impeller 20 side. Outer edges of theplurality of the stationary blades 33 are in contact with the innersurface of the blower housing 40, that is, a lower cover 42. Thestationary blades 33 are juxtaposed in the circumferential direction andguide an airflow S downwardly when the blowing device A is driven.

In the embodiment, the stationary blade 33 and the motor housing 30 arean integral member, but the stationary blade 33 and the motor housing 30may be separate members.

The disk-shaped cover member 50 is disposed below the motor housing 30.The lower surface of the motor housing 30 is covered by attaching thecover member 50. The cover member 50 is fixed to the motor housing 30 byusing fixtures such as screws (not illustrated). The cover member 50 isprovided with a through-hole through which the lead wire passes. Inaddition, as illustrated in FIGS. 1 and 3, the board Bd is disposedbelow the cover member 50.

As illustrated in FIG. 9 which is described later, the intermediatemember 70 is inserted into the facing recess portion 317 provided in thetop plate facing portion 314 of the motor housing top plate 31. Theintermediate member 70 includes a first contact portion 71 and a secondcontact portion 72. The intermediate member 70 is, for example, a heatconduction member made of a material such as silicon resin having a highthermal conductivity (for example, higher than air). Therefore, the heatgenerated by the stator 13 can be transmitted to the motor housing 30via the intermediate member 70. In addition, the intermediate member 70is elastically deformable.

The first contact portion 71 of the intermediate member 70 is in contactwith the coil 133 of the stator 13 of the motor 10. Moreover, the firstcontact portion 71 may be in contact with the stator 13 and is notlimited to the coil 133. However, it is preferable that the firstcontact portion 71 is in contact with the coil 133 which is a heatgeneration source of the motor 10. Therefore, heat generated by the coil133 can be efficiently transmitted to the motor housing 30. In addition,the intermediate member 70 only needs to be in contact with the stator13 and may be is in contact with a portion other than the upper surfaceof the stator 13.

In addition, the second contact portion 72 of the intermediate member 70is inserted into the facing recess portion 317 and is in contact withthe motor housing top plate 31. As described above, the coil 133 isdisposed via the motor housing top plate 31 and the intermediate member70 by providing the intermediate member 70. As described above, sincethe intermediate member 70 is formed of a material having a high thermalconductivity, heat generated by the coil 133 and the stator core 131 byenergization can be transmitted to the motor housing top plate 31 viathe intermediate member 70. The motor housing 30 has a larger surfacearea than that of the stator 13. In addition, since the airflow Sgenerated by the impeller 20 flows along the outer surface of the motorhousing 30, a cooling efficiency increases.

In addition, the intermediate member 70 is an elastically deformablemember. Therefore, even if the stator 13 and the motor housing 30 havemanufacturing errors, it is possible to absorb the errors by elasticallydeforming them. In addition, a lower end portion of the stator core 131is pressed by the axial direction contact portion 321 in the axialdirection. When the stator core 131 is attached to the motor housingcylindrical portion 32, in a state where the intermediate member 70 iselastically deformed, the lower surface of the stator core 131 ispressed by the axial direction contact portion 321. Therefore, rattlingof the stator core 131 can be suppressed and the intermediate member 70can be in contact with the stator 13 and the motor housing top plate 31.

In the blowing device A according to the embodiment, the intermediatemember 70 applies a downward elastic force in the axial direction to thestator 13. The motor 10 includes a plurality of the intermediate members70. The plurality of the intermediate members 70 are disposed with equalintervals around the central axis C, so that it is possible to apply theelastic force to the stator 13 evenly or substantially evenly. In theblowing device A, three intermediate members 70 are provided to be incontact with each of the three coils 133. However, it is not limitedthereto. For example, it is possible to form one intermediate member byusing the annular intermediate member 70.

In addition, it is possible to suppress the movement of the intermediatemember 70 to at least one of the circumferential direction and theradial direction by providing a configuration in which at least a partof the second contact portion 72 of the intermediate member 70 isinserted into the facing recess portion 317 of the motor housing topplate 31. In addition, it is possible to use the intermediate member 70having a longer axial length by inserting the intermediate member 70into the facing recess portion 317. Moreover, in a case where theintermediate member 70 does not move or is difficult to move in thecircumferential direction and/or the radial direction, the facing recessportion 317 is omitted and the second contact portion 72 of theintermediate member 70 may be in contact with the flat or curved topplate facing portion 314. With such a configuration, a step of formingthe facing recess portion 317 can be omitted and it is possible to savetime and labor required for manufacturing of the motor housing 30. Inaddition, it is not limited to the facing recess portion 317 and may beconfigured to include a plurality of projected portions which protrudefrom the top plate facing portion 314 and are in contact with the sidesurface of the intermediate member 70.

Next, the impeller 20 will be described with reference to the drawings.FIG. 8 is a perspective view of the impeller. The impeller 20 is aso-called mixed flow impeller formed of a resin molded article and has ahub portion 21 and a plurality of moving blades 22. The impeller 20 isformed of a resin called engineering plastic. That is, the mixed flowimpeller 20 is formed of resin. The engineering plastic is a resin ofwhich mechanical properties such as strength and heat resistance aresuperior to other resins. Therefore, the mixed flow impeller 20 which isexcellent in characteristics can be realized. Moreover, the impeller 20may be formed of a material such as metal. A diameter of the hub portion21 increases as it goes downwardly. In other words, the impeller 20 hasthe hub portion 21 of which the diameter increases as it goesdownwardly. That is, the hub portion 21 gradually expands downwardly. Inother words, the hub portion 21 expands outwardly in the radialdirection toward the lower side in the radial direction.

The hub portion 21 includes the lower surface recess portion 211 and theboss portion 212. The lower surface recess portion 211 is recessedupward in the axial direction. That is, the hub portion 21 includes thelower surface recess portion 211 which is recessed in the axialdirection. A hole portion 213 into which the shaft 11 of the motor 10 ispress-fitted is provided at a center (on the central axis C) of the bossportion 212. Therefore, the boss portion 212 and the shaft 11 areconnected and the impeller 20 rotates about the central axis C.

The plurality of the moving blades 22 are juxtaposed in thecircumferential direction on an outer surface 214 of the hub portion 21.That is, the plurality of the moving blades 22 are juxtaposed in thecircumferential direction in an outer surface 214 of the hub portion 21.In the embodiment, the moving blades 22 are juxtaposed in thecircumferential direction on the outer surface 214 of the hub portion 21at predetermined intervals and are integrally molded with the hubportion 21. An upper portion of the moving blade 22 is disposed forwardof a lower portion in the rotation direction R. That is, the movingblade 22 is inclined with respect to the central axis C. The impeller 20has the hub portion 21 having a larger diameter as it goes downwardlyand the plurality of the moving blades 22 disposed on the outer surface214 of the hub portion 21. The upper portion of the moving blade isdisposed forward of the lower portion in the rotation direction R.

The lower surface of the hub portion 21 of the impeller has a firstimpeller inclination surface 215 and a second impeller inclinationsurface 216. The first impeller inclination surface 215 is a conicalsurface of which an upper side in the axial direction is inclinedinwardly in the radial direction. That is, the lower surface of theimpeller 20 includes the first impeller inclination surface 215 inclinedinwardly toward the upper side. In addition, the second impellerinclination surface 216 is a conical surface inclined outwardly towardthe upper side in the axial direction on the outside of the firstimpeller inclination surface 215 in the radial direction. That is, thelower surface of the impeller 20 includes the second impellerinclination surface 216 inclined outwardly toward the upper side. Thefirst impeller inclination surface 215 and the second impellerinclination surface 216 are connected at lower ends in the axialdirection. That is, the lower surface of the hub portion 21 has anannular projected portion. The annular projected portion has asubstantially V-shaped cross-sectional shape. When the impeller 20 isfixed to the shaft 11 of the motor 10 which is attached to the motorhousing 30, the first impeller inclination surface 215 faces the firsttop plate inclination surface 311 in the axial direction and the secondimpeller inclination surface 216 faces the second top plate inclinationsurface 312 in the axial direction. Details of the configuration will bedescribed later.

Since the lower surface recess portion 211 of the hub portion 21 of theimpeller 20 is provided, it is possible to reduce the weight of the hubportion 21. The weight of the impeller 20 that is the rotation portionis reduced, so that it is possible to reduce power consumption and makeeasy to rotate the impeller 20 at a high speed. In addition, it ispossible to suppress sink when the impeller 20 is molded.

Next, the blower housing 40 will be described. The blower housing 40surrounds the outside of the motor housing 30 in the radial directionwith a gap therebetween. The blower housing 40 includes the impellercover 41 and the lower cover 42.

The impeller cover 41 is disposed at least on the outside of theimpeller 20 in the radial direction. That is, the impeller cover 41surrounds the outside of the mixed flow impeller 20 in the radialdirection. The impeller cover 41 serves as a guide for directing theflow of the airflow S generated by the rotation of the impeller 20 inthe axial direction. The impeller cover 41 includes the intake port 43that opens in the vertical direction (axial direction). In addition, theintake port 43 includes a bell mouth 431 which bends inwardly from anupper end and extends downwardly. Therefore, the diameter of the intakeport 43 smoothly decreases from the upper side to the lower side. Theimpeller cover 41 includes the bell mouth 431 in the intake port 43, sothat it is possible to smoothly draw the air. Therefore, an amount ofthe air drawing from the intake port 43 during the rotation of theimpeller 20 increases. It is possible to increase the air blowingefficiency of the blowing device A by that much.

In the blowing device A of the embodiment, the impeller cover 41 isfixed to the lower cover 42. As a fixing method, for example, aprojected portion is provided on the outer surface of the lower cover42, and a beam portion, which extends downwardly in the axial directionto the impeller cover 41 and includes a recess portion that is recessedoutwardly in the radial direction on the inner surface of a tip side, isprovided. When the impeller cover 41 is moved in the axial directiontoward the lower cover 42, the beam portion is bent and the projectedportion of the lower cover 42 is inserted into the recess portion of thebeam portion of the impeller cover 41 to fix. Moreover, the fixingmethod, is not limited thereto and it is possible to widely adopt afixing method capable of suppressing movement in the axial direction andthe circumferential direction. It is preferable that it can bepositioned in the circumferential direction and can be easily attachedand detached.

The lower cover 42 is cylindrical in a cross section and extends in theaxial direction. The lower cover 42 is disposed on the outside of themotor housing 30 in the radial direction. That is, the lower cover 42 isdisposed with a gap from the motor housing 30 in the radial direction.The plurality of the stationary blades 33 are juxtaposed in the gapbetween the lower cover 42 and the motor housing 30 with equal intervalsin the circumferential direction. The plurality of the stationary blades33 are in contact with the outer surface of the motor housing 30 in theradial direction.

Moreover, the contact between the stationary blade 33 and the motorhousing 30 includes not only a case of being contact with another memberbut also a case of being formed by integral molding. In addition, thestationary blades 33 are disposed on the outer surface of the motorhousing 30 in the radial direction with equal intervals in thecircumferential direction.

In the motor 10, heat is generated from the coil 133 and the surroundingthereof with the rotation. The heat is transmitted to the motor housing30. The stationary blades 33 protruding outwardly are provided on theouter peripheral surface 300 of the motor housing 30 and the stationaryblades 33 are disposed on the inside of the flow path 60. Therefore, thestationary blades 33 also serve as radiation fins for rectifying theairflow S and for releasing the heat of the motor housing 30 to theoutside. Therefore, the efficiency for cooling the blowing device A dueto the heat generated in the coil 133 and in the vicinity thereofincreases.

Moreover, in the blowing device A of the embodiment, the motor housing30 and the lower cover 42 are formed by integral molding of resin. Theupper end portion of the lower cover 42 includes a penetrating portion421 at a position overlapping the top plate recess portion 313 of thetop plate upper surface 310 of the motor housing top plate 31 of themotor housing 30 in the radial direction. The penetrating portion 421 isa rectangular notch.

The lower cover 42 includes openings at the upper end portion and thelower end portion. The upper end portion of the lower cover 42 isconnected to the lower end portion of the impeller cover 41. The lowerend portion of the impeller cover 41 is inserted into the inside of thelower cover 42. The inner surface of the impeller cover 41 continuessmoothly, for example, differentiably with the inner surface of thelower cover 42. Therefore, the inner surface of the blower housing 40 issmoothed to suppress disturbance of the airflow S.

In the blowing device A of the embodiment, the motor housing 30 and thelower cover 42 are integrally molded, but are not limited thereto. Forexample, the motor housing 30 and the lower cover 42 may be formed asseparate members. In this case, in a state where the impeller 20 isattached to the motor 10 which is attached to the motor housing 30, arotational balance of the impeller 20 is adjusted. Thereafter, since thelower cover 42 can be attached, the penetrating portion 421 of the lowercover 42 may be omitted. In addition, in a case where the lower cover 42is formed as a separate body from the motor housing 30, the impellercover 41 and the lower cover 42 may be integrated.

FIG. 9 is an enlarged sectional view of a cross section (cross sectionincluding the central axis C) along the radial direction of the motorhousing 30 and a circumferential portion of the impeller 20. When theimpeller 20 is fixed to the shaft 11 of the motor 10 which is attachedto the motor housing 30, the first impeller inclination surface 215faces the first top plate inclination surface 311 in the axial directionand the second impeller inclination surface 216 faces the second topplate inclination surface 312 in the axial direction.

An end portion on the inside in the radial direction of the first topplate inclination surface 311 of the motor housing 30 is positionedabove the outer edge in the radial direction of the first impellerinclination surface 215 of the impeller 20 in the axial direction. Inaddition, the outer edge in the radial direction of the second top plateinclination surface 312 is positioned above the end portion on theinside in the radial direction of the second impeller inclinationsurface 216 of the impeller 20 in the axial direction. That is, theannular projected portion configured of the first impeller inclinationsurface 215 and the second impeller inclination surface 216 of theimpeller 20 is disposed on the inside of the annular recess portionconfigured of the first top plate inclination surface 311 and the secondtop plate inclination surface 312 of the motor housing top plate 31.

Moreover, in the blowing device A of the embodiment, a distance D1 ofthe interval between the second top plate inclination surface 312 andthe second impeller inclination surface 216 is the same at the outer endportion in the radial direction and the inner end portion in the radialdirection. Moreover, the “same” includes strictly the same case as wellas the substantially same case.

A distance D2 of the interval between the first impeller inclinationsurface 215 and the first top plate inclination surface 311 is smallerthan the distance D1 of the interval between the second impellerinclination surface 216 and the second top plate inclination surface312. In addition, the end portion on the inside of the first top plateinclination surface 311 in the circumferential direction is disposed ata position higher in the axial direction than the end portion on theoutside of the second top plate inclination surface 312 in the radialdirection. Moreover, the distance D2 of the interval between the firstimpeller inclination surface 215 and the first top plate inclinationsurface 311 may be larger than an interval D1 between an upper endportion 22 u of the moving blade 22 and an impeller cover 411 u.

As described above, the projected portion formed on the lower surface ofthe impeller 20 that is the rotation body is disposed on the inside ofthe recess portion formed in the top plate upper surface 310 of themotor housing top plate 31 facing the lower surface of the impeller 20with an interval. In this case, a minimum dimension of the intervalbetween the motor housing 30 and the impeller 20 is smaller than aminimum dimension of the interval between the motor housing 30 and theimpeller cover 41.

Therefore, an axial labyrinth is formed between the impeller 20 and themotor housing top plate 31. That is, a labyrinth mechanism with a narrowgap can be realized. The axial labyrinth is formed, so that the flow ofthe air is unlikely to occur. Therefore, this makes it difficult for theairflow S generated by the impeller 20 to flow between the impeller 20and the motor housing 30, so that it is easy to maintain the air blowingefficiency. In addition, since the force to the impeller 20 due to theairflow S flowing between the impeller 20 and the motor housing 30hardly acts, the rotation of the impeller 20 is stabilized.

FIG. 10 is a perspective view of the blowing device in a state where theimpeller cover is removed. FIG. 11 is s side view of the blowing deviceillustrated in FIG. 10. As illustrated in FIGS. 10 and 11, the top plateupper surface 310 of the motor housing top plate 31 is provided with thetop plate recess portion 313. The top plate recess portion 313 is arectangular recessed groove having a bottom surface as viewed in theradial direction.

A length r1 of the top plate recess portion 313 in the circumferentialdirection is shorter than a length r2 of the lower end portion of themoving blade 22 of the impeller 20 in the circumferential direction. Asdescribed above, the airflow S generated by the rotation of the impeller20 is unlikely to disturb by narrowing a width of the top plate recessportion 313. Therefore, it is possible to decrease the air blowingefficiency of the blowing device A.

FIG. 12 is a schematic sectional view of a state where balanceadjustment of the impeller is performed. As illustrated in FIG. 12, thetool TL penetrates the penetrating portion 421 of the lower cover 42from the outside into the inside of the lower cover 42. The penetratedtool TL is inserted into the top plate recess portion 313. Asillustrated in FIG. 12, the bottom surface of the top plate recessportion 313 is positioned below the first top plate inclination surface311 and the second top plate inclination surface 312 in the axialdirection. Therefore, the tool TL inserted into the top plate recessportion 313 is positioned below the lower surface of the hub portion 21of the impeller 20.

As described above, a notch portion 23, from which a thick thickness ofthe hub portion 21 is removed by cutting the lower surface of the hubportion 21 of the impeller 20 by the tool TL, is formed. That is, thelower end portion of the hub portion includes the notch portion 23 fromwhich a part of the hub portion 21 is removed. It is possible to adjustthe weight balance of the hub portion 21 in the circumferentialdirection by forming the notch portion 23. Therefore, it is possible tosuppress that the rotation of the impeller 20 is unbalanced. Inaddition, since the impeller 20 is made of a resin, it is easy to cutwith the tool TL and to adjust the rotational balance.

The lower surface of the hub portion 21 of the impeller 20 is positionedat the outermost position in the radial direction in the hub portion 21.When the weight of the lower surface of the hub portion 21 changes, therotation (inertia force) of the impeller 20 tends to change. Therefore,it is possible to optimize the rotational balance of the impeller 20with a small cutting amount by forming the notch portion 23 by cuttingthe lower surface of the hub portion 21.

FIG. 13 is a plan view of the impeller. In FIG. 13, in an innerperipheral surface 411 of the impeller cover 41, a portion at which aninterval with the upper end portion 22 u of the moving blade 22 in theaxial direction is minimized is illustrated by a two-dot chain line as411 u. In addition, in the inner peripheral surface 411 of the impellercover 41, a portion at which an interval with a lower end portion 22 dof the moving blade 22 in the axial direction is minimized isillustrated by a two-dot chain line as 411 d.

Normally, in the blowing device, the smaller the interval between themoving blade 22 of the impeller 20 and the inner peripheral surface 411of the impeller cover 41, the higher the air blowing efficiency.However, in a case where the interval between the moving blade 22 andthe inner peripheral surface 411 is not appropriate, the air blowingefficiency may be lowered. Therefore, it is preferable that the intervalbetween the moving blade 22 and the inner peripheral surface 411 isappropriate.

When the impeller 20 rotates, a centrifugal force acts on the hubportion 21 and the moving blade 22. In the hub portion 21, the lowerside in the axial direction has a larger diameter than that of the upperside. Therefore, the centrifugal force in the outer edge in the radialdirection differs between the upper side and the lower side of theimpeller 20. Since the centrifugal force is different, an amount ofdeformation due to the centrifugal force also varies. Since the outeredge of the moving blade 22 in the radial direction is farther from thecentral axis C on the lower side than the upper side, the centrifugalforce of the lower side is larger than that of the upper side. That is,the amount of deformation to the outside of the moving blade 22 in theradial direction during the rotation of the impeller 20 is larger on thelower side than on the upper side.

The hub portion 21 expands larger on the lower portion than on the upperportion. Therefore, the amount of deformation of the lower portion ofthe hub portion 21 is larger than that of the upper side thereof.Therefore, the lower surface recess portion 211 is provided on the lowersurface of the hub portion 21, the hub portion 21 is thin in the radialdirection and is easily deformed by the centrifugal force. The lowerportion of the hub portion 21 has a conical shape. Therefore, the lowerportion of the hub portion 21 is deformed outwardly and upwardly by therotation of the impeller 20. Therefore, the lower end portion 22 d ofthe moving blade 22 is deformed outwardly in the radial direction andupwardly. In addition, the upper end portion 22 u of the moving blade 22is deformed outwardly in the radial direction and downwardly.

Taking together the above, when the impeller 20 rotates, that is, theblowing device A performs an air blowing operation, the amount ofdeformation of the moving blades 22 of the impeller 20 in thecircumferential direction is larger at the lower end portion 22 d in theaxial direction than at the upper end portion 22 u in the axialdirection.

In addition, the inner peripheral surface 411 (see FIG. 3) of theimpeller cover 41 has a shape expanding outwardly toward the lower sidein the axial direction. Therefore, the upper end portion 22 u of themoving blade 22 is deformed in a direction (see FIG. 3) along the innerperipheral surface 411 of the impeller cover 41. On the other hand, thelower end portion 22 d of the moving blade 22 is deformed in a direction(see FIG. 3) intersecting the inner peripheral surface 411 of theimpeller cover 41. Therefore, the interval between the moving blade 22and the inner peripheral surface 411 tends to narrow due to deformationcaused by the centrifugal force during the rotation of the impeller 20.

In the blowing device A, a minimum dimension t1 of the gap between thelower end portion 22 d of the moving blade 22 and the inner peripheralsurface 411 of the impeller cover 41 is larger than a minimum dimensiont2 of the gap between the upper end portion 22 u of the moving blade 22and the impeller cover 411 u of the impeller cover 41. That is, theminimum dimension t1 of the gap between the moving blade 22 and theinner peripheral surface 411 d at the lower end portion 22 d of themoving blade 22 is larger than the minimum dimension t2 of the gapbetween the moving blade 22 and the impeller cover 411 u at the upperend portion 22 u of the moving blade 22. Therefore, even in a case wherethe impeller 20 rotates at a high speed, it is possible to appropriatelymaintain the gap between the moving blade 22 and the inner peripheralsurface 411 of the impeller cover 41. Therefore, it is possible tostably and smoothly rotate the impeller 20.

The cleaner 100 includes the blowing device A. In the cleaner 100 havingthe configuration described above, when the motor 10 of the blowingdevice A is driven, the impeller 20 rotates in the rotation direction Rabout the central axis C. Therefore, the air containing trash such asdust on the floor surface F circulates through the suction nozzle 110,the suction pipe 107, the intake portion 103 (see FIG. 1), the dustcollecting portion, and the filter in order. The air passing through thefilter is drawn in the inside of the blower housing 40 via the intakeport 43 of the blowing device A. In this case, an amount of the airwhich is drawn in from the intake port 43 is increased by the bell mouth431 and the air is smoothly guided between the adjacent moving blades22. Therefore, it is possible to improve the air blowing efficiency ofthe blowing device A. Moreover, since the cleaner 100 includes theblowing device A, even in a case where a strong centrifugal force isgenerated during the driving of the cleaner 100, it is possible tosuppress that the efficiency of the cleaner 100 decrease.

The air drawn in the inside of the impeller cover 41 circulates throughbetween the adjacent moving blades 22 and is accelerated outwardly inthe radial direction and downwardly by the rotating impeller 20. The airwhich is accelerated outwardly in the radial direction and downwardly isdrawn out downwardly from the impeller 20. The air which is drawn outdownwardly from the impeller 20 flows through the flow path 60 of thegap between the motor housing 30 and the lower cover 42. The air flowinginto the flow path 60 circulates through between the stationary blades33 adjacent in the circumferential direction.

The airflow S passing through the lower end of the stationary blades 33is exhausted to the outside of the blower housing 40 via the exhaustport 61. The airflow S exhausted to the outside of the blower housing 40circulates through the air passage in the casing 102 of the cleaner 100and is exhausted from the exhaust portion 104 (see FIG. 1) to theoutside of the casing 102. Therefore, the cleaner 100 can clean thefloor surface F.

In the motor 10, the coil 133 and the stator core 131 generate heat dueto energization to the coil 133. The first contact portion 71 of theintermediate member 70 is in contact with the coil 133, the secondcontact portion 72 is inserted into the facing recess portion 317, andthe second contact portion 72 is in contact with the motor housing topplate 31. Therefore, the intermediate member 70 transmits the heatgenerated by the coil 133 and the stator core 131 to the motor housingtop plate 31. The motor housing top plate 31 is integrally formed withthe motor housing cylindrical portion 32 and the airflow S generated bythe impeller 20 flows through the outer surface of the motor housingcylindrical portion 32. In addition, the plurality of the stationaryblades 33 integrally formed with the outer surface of the motor housingcylindrical portion 32 are provided on the inside of the flow path 60through which the airflow S flows. Therefore, the surface area withwhich the airflow S is in contact increases and a heat radiationefficiency increases. Therefore, it is possible to decrease thetemperature of the motor 10 and to suppress the decrease in theefficiency due to the heat of the motor 10 by providing the intermediatemember 70. As a result, it is possible to suppress the decrease in theair blowing efficiency of the blowing device A.

In addition, an annular impeller projected portion 11 p is provided onthe lower surface of the hub portion 21, and an annular groove portion21 g which is recessed downwardly is provided on the upper surface ofthe motor housing 30. At least a part of the impeller projected portion11 p is accommodated in the groove portion 21 g. Therefore, it ispossible to prevent the airflow circulating through the flow path 60from flowing through the inside (see FIG. 3) of the impeller 20 whilesuppressing an increase in size of the blowing device A in the axialdirection. That is, a labyrinth effect is exerted. Therefore, it ispossible to improve the air blowing efficiency of the blowing device A.

FIG. 14 is a plan view illustrating a modification example of a topplate recess portion. As illustrated in FIG. 14, similar to the topplate recess portion 313, a top plate recess portion 318 is recesseddownwardly from the top plate upper surface 310. In addition, the topplate recess portion 318 extends outwardly from the inside in the radialdirection. The inside of the top plate recess portion 318 in the radialdirection is disposed backwardly in the rotation direction of theimpeller 20 from the outside of the top plate recess portion 318 in theradial direction.

The moving blades 22 included in the impeller 20 are mixed flow blades.Therefore, the airflow generated by the rotation of the impeller 20includes a component of the rotation direction R of the impeller 20,that is, a component of the circumferential direction. The airflow inFIG. 14 includes a component facing backward of the rotation direction Rof the impeller 20. That is, the airflow flows downwardly in the axialdirection and flows outwardly in the radial direction and backwardly inthe rotation direction of the impeller 20.

The inside of the top plate recess portion 318 in the radial directionis disposed backwardly in the rotation direction of the impeller 20 fromthe outside in the radial direction. Therefore, the airflow flows in adirection intersecting a longitudinal direction of the top plate recessportion 318. It is difficult for the airflow to flow through the topplate recess portion 318 and it is possible to suppress disturbance ofthe airflow by adopting such a shape.

FIG. 15 is a sectional view of the top plate recess portion in thecircumferential direction. The airflow flows intersecting the top platerecess portion 313 and the top plate recess portion 318 when the blowingdevice A is viewed from above in the axial direction. In this case, theairflow flows into the inside of the top plate recess portion 313 andthe top plate recess portion 318, and disturbance of the airflow tendsto occur. Therefore, a top plate recess portion 319 illustrated in FIG.15 includes a recess portion front side surface 3190 that is a sidesurface of a front side of the impeller 20 of the top plate recessportion 319 in the rotation direction. The recess portion front sidesurface 3190 includes the front side surface enlarged portion 3191 whichexpands forward the impeller 20 in the rotation direction toward theupper side.

The front side surface enlarged portion 3191 is provided in the recessportion front side surface 3190, so that even in a case where the air isguided to the top plate recess portion 319 by the rotation of theimpeller 20, since the air is smoothly exhausted along the front sidesurface enlarged portion 3191, it is possible to suppress that theairflow enters the inside in the radial direction. In addition, since itis possible to suppress that turbulence generates in the top platerecess portion 319 and in the vicinity thereof it is possible tosuppress the decrease in the air blowing efficiency. Moreover, in FIG.15, the front side surface enlarged portion 3191 is a curved surfaceprojected upwardly, but is not limited thereto. For example, the frontside surface enlarged portion 3191 may be a flat surface, or may be acurved surface recessed downwardly.

FIG. 16 is an enlarged sectional view of a cross section (cross sectionincluding the central axis C) along the radial direction of the motorhousing. FIG. 16 illustrates only one side in the radial direction withrespect to the central axis C. As described above, when the airflow isgenerated by the rotation of the impeller, if there is the top platerecess portion 313 on the top plate upper surface 310 of the motorhousing top plate 31, there is a concern that the airflow is disturbed.Therefore, as illustrated in FIG. 16, an insertion member 34 may beinserted into the top plate recess portion 313 to fill the top platerecess portion 313. It is possible to suppress that the airflow flowsinto the top plate recess portion 313 by filling the top plate recessportion 313, so that it is possible to suppress disturbance of theairflow. It is preferable that the insertion member 34 has a shape thatis flush with the top plate upper surface 310 of the motor housing topplate 31. Moreover, the insertion member 34 has a size capable ofinserting from the penetrating portion 421. Moreover, in a case of aconfiguration in which the lower cover 42 is capable of separating fromthe motor housing 30, and in a case of a configuration in which thelower cover 42 is capable of separating from the impeller cover 41, thesize of the insertion member 34 is not limited to the penetratingportion 421.

In addition, the penetrating portion 421 is provided in the lower cover42. The lower cover 42 configures the flow path 60 and when the airflowleaks from the penetrating portion 421, the air blowing efficiencydecreases. Therefore, outflow of the airflow is suppressed by blockingthe penetrating portion 421 with a lid portion 422. Therefore, thedecrease in the air blowing efficiency is suppressed.

Although the exemplary embodiments of this disclosure have beendescribed above, various modifications can be made to the embodimentswithin the scope of the gist of this disclosure.

Exemplary embodiments of this disclosure may be utilized, for example,in a blowing device and a cleaner equipped with the same.

Features of the above-described preferred embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While preferred embodiments of the present disclosure have beendescribed above, it is to be understood that variations andmodifications will be apparent to those skilled in the art withoutdeparting from the scope and spirit of the present disclosure. The scopeof the present disclosure, therefore, is to be determined solely by thefollowing claims.

What is claimed is:
 1. A blowing device comprising: a mixed flowimpeller that rotates about a central axis extending vertically; a motorthat drives the mixed flow impeller to rotate; and an impeller coversurrounding an outside of the mixed flow impeller in a radial direction;wherein the mixed flow impeller includes: a hub portion that expandsoutwardly in the radial direction toward a lower side in an axialdirection; and a plurality of moving blades which are juxtaposed on anouter surface of the hub portion in a circumferential direction; and aminimum dimension of a first gap between the moving blade and theimpeller cover at a lower end portion of the moving blade is larger thana minimum dimension of a second gap between the moving blade and theimpeller cover at an upper end portion of the moving blade.
 2. Theblowing device according to claim 1, wherein the hub portion includes alower surface recess portion that is recessed in the axial direction ona lower surface.
 3. The blowing device according to claim 1, wherein themotor is disposed below the mixed flow impeller; a motor housing whichsurrounds an outside of the motor in the radial direction is provided;and a minimum dimension of a third gap between the motor housing and theimpeller is smaller than a minimum dimension of a fourth gap between themotor housing and the impeller cover.
 4. The blowing device according toclaim 2, wherein the motor includes: a shaft extending along the centralaxis; a rotor that is fixed to the shaft and rotates together with theshaft; an upper bearing that rotatably supports the shaft; and a lowerbearing that is disposed below the upper bearing and rotatably supportsthe shaft; and at least a portion of the upper bearing is disposed inthe lower surface recess portion.
 5. The blowing device according toclaim 1, wherein a lower end portion of the hub portion includes a notchportion obtained by removing a portion of the hub portion.
 6. Theblowing device according to claim 1, wherein the mixed flow impeller ismade of resin.
 7. A cleaner comprising: the blowing device according toclaim 1.